Spark-plug.



F. J. WATT.

SPARK PLUG. APPLICATION Hum SEPT. 9,1908.

Patented Mar. 9, 1909.

9 10 Fig. 8. 13% 3.

WITNESSES: INVENTOR 0mm 00. Frank J. Watt a 2%. 99W By ATTORNEY/5'UNITED STATES PATENT oFFioE.

FRANK J. WATT, OF DETROIT, MICHIGAN.

SPARK-PLUG.

To all whom it may concern:

Be it known that I, FRANK J. WATT, a citi- I zen of the United States ofAmerica, residing part of-the bushing and the nipple.

at Detroit, in the county of Vi ayne and State of Michigan, haveinvented'certain new and useful Improvements in Sp ark-Plugs, of whichthe following is a specification, reference being had therein to theaccompanying drawings.

This invention relates to spark plugs for explosive engines, and moreespecially to means therein whereby leakage and breakage from unequalexpansion is avoided, and the construction greatly simplified.

The invention consists in the matters hereinafter set forth, and moreparticularly pointed out in the appended claims.

In the d ti'ally in elevation and Specification of Letters Patent.Application filed September 9, 1908.

i i i i i I i i i i Patented March 9, 1909. Serial No. 452,245.

The head is proportioned to leave an annular air space between it andthe insulating bushing. The upper projecting end of the stem isscrew-threaded for a clam ing nut 9 which bears against a spring was or10 and soft washer 11 of asbestos or the like. The spring washer has aplurality of inner arms 12 bent alternately in opposite directions and asolid rim. A ca) 16 is seated on the washer rim over the camping nut anda hand nut 13 forming with the cap a binding post is placed on the stemoutside the cap.- There is a sparking terminal 14 on the nipple and anaxial one 15 on the stem in operative relation thereto. By thisarrangement, the insulating bushing is held in place without the use ofan outer clamping collar or cap, as in the rawiiigs, Figure 1 is a view,par-i usual construction, and is free to expand partially in section ofwithout liability to fracture.

The stem is yieldingly seated against the inner bushing a spark plugembodying features of the invention. Fig. 2 is a view in detail of aspring by the spring washer so that expansion or conwasher. Fig. 3 is aview in section of the traction does not affect it. Furthermore, Washer.the joint between this bushing and the stem screw-threaded portion, awasher 5 of pro er material insuring a tight joint and there eing anannular air space between the lowfiar T e ead of the bushing extendswell above the nipple and is enlarged to overhang and protect the nipplerim. The axial aperture of the bushing is counterbored from the lowerend and a metal bushing 6 cemented therein or otherwise pro of thebushing 6 eing screw-threaded, corrugated or roughened to anchor itfirmly in the cement which adheres closely to the unglazed inner surfaceof the porcelain. The lower end of the bushing 6 is turned or faced offsquare.

A metal stem 7 extends axially through the bushing 3 and has'a head 8shouldered to seat itself closely on the lower end of the inner bushingand form a tight joint therewith.

erly secured, the periphery I head is readily made air tight by roperdressing of the metals, the diflioulty of making a close fit betweenmetal and the vitreous, irregularly surfaced insulating bushing beingavoided.

hat I claim as my invention is 1. A spark plug for an explosive enginecomprising a tubular metal nipple, a bush ing of insulating materialscrew-threaded into the iii ple, a metal bushing secured in the bore ofthe insulating bushing mediate its ends, a metal stem extending throughthe insulating bushing having a head seated on the inner metal bushing,a spring Washer on the stem, a clam ing nut foroin the washer againstthe insulating bushing liead, a terminal on the stem and one on thenipple in operative relation thereto.

2. A spark plug for an explosive engine comprisin a tubular metalnipple, an insulating bus ing of refractory material screwthreaded intothe nipple having a counterbored lower end, a metal bushing seated inthe counterbore, a metal stem extending through the inner bushing havinga head ada ted to be seated on the end of the inner busliingand ascrew-threaded upper end extending above the insulating bushing head, aspring washer on the stem and bushing head, a c'lamping nut on the stemengaging the spring washer, a cap on the stem over the clamping nutbearing against the Washers, a

' {terminal on the stem osite directions a clamping nut on the stemeating a t: the spring arms, a ca over the nut seated on the rim, a nuton t e stem outside the cap, a terminal on the head of the stem, and aterminal on the nipple in operative relation thereto.

5. A spark plug for an explosive engine comprising an lnteriorlyscrew-threade a ternately in op on the stem beyond the ca the lower endof the nipp e and ead. 3. A spark plug for an explosive engine"comprising an interiorly screw; threaded metal nipple, an insulatmgbushing of refractory material having an exteriorly screwthreadedportion engaging the nipple screwhand nut minal on throu h the mner adate to be seated bus ing and a screwabove the ininetal stem 'extendinlating Washer g head on the end of the inner threaded upper endextending sulating bushing head, an on the stem and bushing msu head, aspr ng threads, a lower portion of less diameter than metal nipple, aninsulating bushing of rethe nipple extendin concentrically therefractorymaterial having an exteriorly screw throug and a hea projecting abovethe threaded portion engaging the nipple screw- 1e, a metal bushingpermanently secured threads, a lower portion of less diameter than n einsulating bushing mediate its ends, a the hi ple extendingconcentrically there metal stein extendingthroughtheinnerbushthroug anda hea projegting above the lng havin a eadadapted to be seated onnippnle', a metal bushing per anently secured the end of the innerbushing and a screwin t e insulating bushing mediate its ends, a

washer on the insulating Washer, a clam ing threaded uppelrk endextending above thoinnut on the stem engaging the spring was er,sulating bus g head, a washer of insulating a ca on the stem overtheclamping nut material on the upper end of the bushing, a bearing againstthe washers, a hand nut on 'sprin washer having a solid rim an innercomprising a tubu the stem v stem head,

the upper end rim and inner radial spring arms beyond the cap, aterminal on the alternately in oppolower end of the nipple, and aterminal on the 4. A spark plug for an explosive engine ar metal nipple,abushjng of insulating material screw-t the nipple, a metalbushingsecured in-the bore ofthe insulating bushing mediate its ends, ametal stem extending through the insulating bushing having a head seatedon the innernietalbushing, a spring washer on of the bushing having asolid bent alter- Witnesses; O'r'ro FJBARTHEL, C.R.;STIOKNEY.\

on the stem two Witnesses.

FRANK J. WATT.

